Fuel feeding system



1939. R. F. BRACKE L FUEL FEEDING SYSTEM Filed Jan. 16, 1936 2' Sheets-Sheet 1 Ill //IIII Aug. 22, 1939.

R. F. BRACKE 2,170,651

FUEL FEEDING SISTEM Filed Jan. 15, 1936 ZShee'ts-Sheet 2 Patented Aug. 22, 1939 UNITED STATES PATENT OFFICE 3 Claims.

My invention relates to fuel feeding systems and is particularly concerned with the fuel feeding systems for internal combustion engines.

The suction created by the suction strokes of 5 the pistons of an internal combustion engine has commonly been used as a means for sucking fuel from a main fuel tank to the fuel chamber of the engine carburetor. In automotive vehicles particularly the main fuel tank is located below and at some distance from the carburetor so that an appreciable degree of suction is required to draw fuel from the main tank to the carburetor. The suction created by the pistons varies with different conditions of engine operation, and under certain conditions of operation is insufficient to accomplish this purpose.

An object of my invention is to provide a fuel feeding system utilizing the engine suction for withdrawing fuel from the main fuel tank to the carburetor float bowl and wherein the variable suction created by the engine is modified to provide a uniform suction head for raising fuel.

Another object of my invention is to provide a fuel feeding system which utilizes the suction created by the engine pistons to draw fuel from. a main fuel tank located below and at some distance from the engine carburetor to the float bowl of the carburetor and wherein the suction created by the engine isamplified under certain conditions and reduced under certain other conditions.

Another object is to provide a fuel feeding system of the foregoing type wherein the suction utilized to draw fuel from the main fuel supply tank to the float chamber of the carburetor is never permitted to increase to such a point that boiling of the fuel will result or that difliculty will be experienced with leakage into a suction chamber.

Other objects and advantages will appear as the description proceeds.

In the drawings,

Figure 1 is a sectional view through one form of carburetor assembly embodying my invention and shows diagrammatically the fuel line connecting this assembly with the main fuel tank and the suction line connecting this carburetor assembly with a part of the intake manifold of an internal combustion engine;

Figure 2 is a vertical section through a modified form of carburetor assembly; and

Figure 3 is a vertical section through a further modified form of carburetor assembly having a different suction connection from the suction connections shown in Figures 1 and 2.

Referring to Figure 1 of the drawings, I have shown a carburetor assembly having a secondary air inlet [0 leading to a mixing chamber l2 into which a nozzle 14 discharges. The mixing chamber I2 communicates with the inlet passage l6 of the engine manifold, and a throttle valve [8 is provided to control the communication between the passage I6 and the mixing chamber I2.

An idling jet 20 is located immediately below the closed position of the throttle valve I8, and the usual choke 22 is provided for reducing the secondary air supplied to facilitate starting of the engine when cold. It will be understood that the choke 22 and throttle valve l8 are connected to the usual controls of an automobile or other vehicle.

The nozzle l4 and idling jet 20 are supplied with fuel from a float chamber 24 by means of a conduit 28. In float chamber 24 is a float 28 pivoted at so. This float is so positioned with respect to the flap valve 32 that when the float chamber 24 contains suflicient fuel the float 28 rises to the position indicated in Figure 1 of the drawings and holds the inlet valve 32 closed to prevent the admission of further fuel into the float chamber 24.

A vacuum chamber 34 is located above the float chamber 24 and communicates therewith by means of passage 36 and valve 32. This vacuum chamber 34 is connected to the main fuel supply tank 38 by means of conduit 40. In automotive practice it is usual to mount the main tank 38 at the rear of the automobile and at a level below that of the carburetor assembly. Means must therefore be provided to raise the fuel from the tank 38 to the chamber 34.

My invention contemplates the use of the suction created in the intake manifold of the internal combustion engine for drawing the fuel from the main tank 38 to the chamber 34. In this Figure 1 I have shown a booster Venturi tube having an inlet 44 communicating with the secondary air inlet I0. Since the secondary air inlet of the carburetor is adapted to be provided with an air cleaner, the booster Venturi tube 42 receives clean air through the inlet 44.

The outlet end of the Venturi tube 42 is connected by conduit 46 with a section 48 of the intake manifold of the internal combustion engine. In the form shown in the drawing the manifold section 48 serves only a single cylinder and is cut off from the rest of the intake manifold by a valve '58 which is urged against its seat by a spring 52. The suction created by the cylinder supplied by the manifold section 48 serves to draw the valve from its seat during engine operation, and the stem 54 of the valve 50 is preferably provided with a piston 55 operating in a dash pot cylinder 58 to reduce fluttering of the valve.

The throat of the booster Venturi tube 42 is provided with radial pasages 60 communicating with a duct 62 opening into the top of the chamber 34. A second duct 64 connects the upper end of the chamber 34 with atmosphere by Way of the secondary air inlet I 0.

The ducts 62 and 64 are controlled by valves 66 and 68, respectively, mounted on a common stem 70 in such manner that when. one valve is closed the other is opened. a

The valves 66 and 68 are controlled by a float 12 through a snap action connection consisting of links M and 16 having their adjacent ends carried on av common pivot 18 and their outer ends connected to the valve stem 10 and float 72, respectively. A tension spring 89 is connected to the outer ends of the links M and 1B and tends to draw these ends toward each other.

When the chamber 34 is full of fuel, as indicated in Figure 1, the float 12 rises and closes valve 66 and opens valve 68. In this position of the fioat and valves the chamber 34 is open to atmosphere and the fuel therein may flow by gravity into the float chamber 24 in accordance with the fuel requirements of the engine. When the fuel level in the chamber 3t drops, the float drops with it and valves 68 and 68 are shifted by a snap action to cut oiT the atmospheric communication with the chamber 35 and to connect this chamber with the throat of the booster Venturi tube 5,2. The suction then existing in the throat of this booster is communicated to the chamber 34 and is available for lifting fuel thereto from the main fuel tank 38.

All of the mechanism so far described may be identical with that disclosed and claimed in my prior application, Serial No. 12,156, filed March 21, 1935 now Patent Number 2,131,036.

The suction existing in the intake manifold of an internal combustion engine varies from a maximum when the engine is idling to a minimum when the engine is operating under full throttle at low speed. The valve 50, located in the intake manifold, raises the minimum suction which exists in the manifold section 4.8 when the engine is operating at low speeds under full throttle, but it is inadvisable to construct this'valve so that it will greatly restrict the flow of combustible mixture to the cylinder supplied from the manifold section =38. The degree of suction existing in the manifold section 58 therefore varies considerably for difierent conditions of engine operation, although this variation is less than the variation which occurs in the rest of the intake manifold.

If the booster Venturi tube 42 is so designed that the requisite suction is created in the chamber 32 when the minimum suction exists in manifold section 88, then an undesirably high suction will be created in the chamber 34 when the maximum suction exists in the manifold section 48. This undesirably high suction in the chamber 34 wiil tend to cause boiling of the gasoline in the chamber 35 and will also make it difiicult to prevent leakage into this chamber. Such leakage may be either in the form of back flow of vapor past the valve 32 or air leakage past the valve 18. In addition to the high degree of suction reated in the chamber 34, the structure thus far described has the additional objection that relatively large quantities of air are drawn through the booster Venturi tube 42 into the intake manifold during engine idling. This dilutes the idling mixture in the part of the manifold into which the conduit 46 discharges and results in irregular idling of the engine.

My present invention is particularly concerned with means for preventing the creation of this unduly high suction in the'chamber 34 and with means for preventing the introduction of relatively large quantities of air into the intake manifold of the engine while it is idling. In Figure l of the drawings, the means for accomplishing both of these purposes comprises a rotary valve 82 located in the discharge end of the booster Venturi tube 42 to control the flow therethrough. This rotary valve 82 has an arm 84 connected by a link 86 to a second arm 38 rotatable with the throttle valve l8.

The connection between the throttle valve l8 and the rotary valve 82 is such that when the throttle valve is fully open the .rotary valve 82 is fully open, as shown in Figure 1 of the drawings. This means that when the suction in the intake manifold is low, a maximum amount'of air is admitted through the booster Venturi tube 42 whereupon this booster efie'cts a maximum amplification of the manifold suction to increase it sufliciently to insure the desired degree of suction in the chamber 34.

As the throttle valve is is closed and the manifold suction is thereby increased, the valve 32 is likewise partly closed to reduce the flow of air through the booster 42, thereby reducing the suction multiplying effect of this booster. When the throttle valve i8 is in its fully closed position, the rotary valve 82 is very slightly opened so that the suction created in the chamber 34 is materially less than that existing in the intake manifold.

In the modification shown in Figure 2 of the drawings, the rotary valve 82 is eliminated and in lieu thereof an automatic pressure valve H30 is interposed between the chamber 34 and atmosphere. This valve N20. is normally held in closed position, by a spring I02 which is given such tension that valve H10 opens upon the creation of a predetermined suction in the chamber 34. The opening of the valve 10G admits air to the .chamber 34, and thereby prevents further in- .crease in the suction existing in this chamber.

In the modification shown in Figure .3, both the rotary valve 82 of Figure 1 and the automatic pressure valve in of Figure 2 are dispensed with. In this form of my invention the choke valve 22 of the previous embodiments is supplanted by a secondary air valve HE which is urged toward closed position by a spiral spring I I2. The valve H6 is eccentrically pivoted and is opened by the pressure exerted by the air on the right-hand side of this valve, as viewed in the drawings.

Instead of being connected with a section of the intake manifold, the outlet of the booster Venturi tube i2 in this form of my invention is connected by a conduit I'M with the carburetor mixing chamber l2. The suction variation in the mixing chamber 1 2 is much less than the suction variation in the manifold section 38 so that the booster Venturi tube 472 may be designed to produce the requisite suction in the chamber 34 when the mixing chamber suction is at a minimum, and when the mixing chamber suction is at a maximum the. increased suction in the chamber 34 will not be high enough to create boiling of the fuel therein or to cause undesirable leakage past the valves 32 and 68.

The float chamber 24 is provided with a port H6 which connects the upper part of this float chamber with the carburetor mixing chamber l2. The suction available to lift fuel from the float chamber 24 to the nozzle I4 is thus the result of the suction multiplying effect of the Venturi tube which forms this nozzle.

The booster Venturi tube 42 and conduit H4 constitute a small bypass around the secondary air valve H0 and this secondary air valve is so designed that when it is closed it fits tighter than does the usual secondary air valve and thereby compensates for this bypass. During choking of the engine the secondary air valve is held closed by a finger l l8 which is pivoted just below the secondary air valve and which may be moved about its pivot so as to engage the under side of the air valve and hold it closed.

In this form of my invention the secondary air valve I 10 may be considered as performing the functions of the valve 82 of Figure 1 and the valve lfiil of Figure 2. In this Figure 3 form of my invention the secondary air valve I ll! automatically prevents the creation of an unduly high suction in the mixing chamber I I2 and thereby prevents the creation of an unduly large flow through the booster 42, such as would produce an undesirably high suction in the vacuum chamber 34. The air passing through the booster 42 enters the mixing chamber of the carburetor where it has an opportunity to thoroughly mix with the other ingredients of the combustible mixture supplied to the engine cylinders, thereby improving engine operation.

In the embodiment of Figures 1 and 2, the discharge pipe of the booster is shown as connected with a section of the inlet manifold which is restricted by the valve 50. This valve is not essential to the operation of my invention and may be dispensed with, although I find it to be desirable for most installations. Furthermore, where this valve 50 is utilized, the section of the manifold controlled thereby is not necessarily limited to supplying a single cylinder of the engine but may supply combustible mixture to all of the cylinders or any number thereof.

While I have shown only three forms of my invention, it is to be understood that my invention is not limited to the details of the embodiment shown but is capable of assuming numerous forms, and that the scope of my invention is to be limited solely by the following claims.

I claim:

1. In a fuel feeding system. for internal combustion engines having intake manifolds, the combination of a carburetor having a float chamber, a fuel feeding nozzle communicating with and supplied with fuel from said float chamber, a mixing chamber into which said nozzle discharges, said mixing chamber adapted to communicate with an intake manifold, a vacuum chamber, means including a passageway, a valve and a float in said float chamber for controlling communication between said' float chamber and said vacuum chamber, a main fuel tank spaced from said vacuum chamber, a pipe connecting said fuel chamber with said vacuum chamber, a throttle valve controlling communication between said mixing chamber and intake manifold, a Venturi tube discharging into the intake manifold, a connection between said vacuum chamber and the throat of said Venturi tube, a float in said vacuum chamber controlling said communication and also controlling communication between said vacuum chamber and atmosphere, and a valve for limiting the degree of suction created in said vacuum chamber.

2. In a fuel feeding system for internal combustion engines having intake manifolds, the combination of a carburetor having a float chamber, a fuel feeding nozzle communicating with and supplied with fuel from said float chamber, a mixing chamber into which said nozzle discharges, said mixing chamber adapted to communicate with an intake manifold, a vacuum chamber, means including a passageway, a valve and a float in said float chamber for controlling communication between said float chamber and said vacuum chamber, a main fuel tank spaced from said vacuum chamber, a pipe connecting said fuel tank with said vacuum chamber, a throttle valve controlling communication between said mixing chamber and intake manifold, a Venturi tube discharging into the intake manifold, a valve for modifying flow through said Venturi tube, a link connecting said throttle valve and said last-named valve, a connection between said vacuum chamber and the throat of said Venturi tube, and valve means controlling communication through said connection and also controlling communication between said vacuum chamber and atmosphere.

3. In a fuel feeding system for internal com.- bustion engines having intake manifolds, the combination of a carburetor having a float chamber, a fuel feeding nozzle communicating with and supplied with fuel from said float chamber, a mixing chamber into which said nozzle discharges, said mixing chamber adapted to communicate with an intake manifold, a, vacuum chamber located immediately above said float chamber, means including a passageway, a valve and a float in said float chamber for controlling communication between said float chamber and said vacuum chamber, a main fuel tank spaced from said vacuum chamber, a pipe connecting said fuel tank with said vacuum chamber, a throttle valve controlling communication between said mixing chamber and intake manifold, a Venturi tube discharging into the intake manifold, a valve for modifying flow through said Venturi tube, a link connecting said throttle valve and said last-named valve, a connection between said vacuum chamber and the throat of said Venturi tube, and a float in said vacuum chamber controlling said connection and also controlling communication between said vacuum chamber and atmosphere.

ROBERT F. BRACKE. 

